1. Field of the Invention
The present invention relates to a hydraulic system for controlling a motor vehicle transmission with automated actuation of clutches, the system including a first valve connected downstream from a hydraulic energy source for producing a system pressure, to control and/or regulate a clutch pressure. A second valve is connected downstream from the first valve and ahead of two clutches of the motor vehicle transmission with automated actuation of clutches to control and/or regulate the clutch pressure.
2. Description of the Related Art
Motor vehicle transmissions with automated actuation of clutches can be semi-automated, automated, or automatic transmissions. They are, for example, a shift transmission with electric clutch management, in which the clutch is actuated automatically, an automated shift transmission, for example a dual-clutch transmission, an automatic transmission with a stepped automation unit, or a continuously variable automatic transmission (CVT), such as, for example, a belt-driven conical-pulley transmission.
Hydraulic systems for controlling a motor vehicle transmission with automated actuation of clutches are known. In such hydraulic control systems, electrical proportional valves can be employed in order to convert an electrical current to a hydraulic pressure. Individual functions of the hydraulic system can be actuated with the aid of that pressure. It is known to employ such hydraulic systems for motor vehicles having a so-called “shift-by-wire” functionality. It is also known to employ proportional valves that have a screen at an inlet of the proportional valve.
An object of the present invention is to provide an improved hydraulic system for controlling a vehicle transmission having automated actuation of clutches, in particular one that is more robust against occurrence of a back pressure under cold conditions, preferably using proportional valves having an inlet screen.